In a study on an organic electroluminescent (EL) device (hereinafter, simply referred to as ‘organic EL device’), which has continued from the start point of observing an organic thin film light emission by Bernanose in the 1950s to blue electric light emission using an anthracene single crystal in 1965, an organic EL device having a lamination structure, which is divided into functional layers of a hole layer and a light-emitting layer, was proposed by Tang in 1987. Until now, the organic EL device has been developed in the form of introducing each characteristic organic material layer into a device in order to manufacture the organic EL device having high efficiency and a long service life (lifespan), thereby leading to the development of specialized materials used therein.
When voltage is applied between two electrodes of the organic EL device, holes are injected into the organic material layer at the anode and electrons are injected into the organic material layer at the cathode. When the injected holes and electrons meet each other, an exciton is formed, and when the exciton falls down to a bottom state, light is emitted. Materials used as the organic material layer may be classified into a light-emitting material, a hole injection material, a hole transporting material, an electron transporting material, an electron injection material, and the like according to the function.
Materials for forming the light-emitting layer of the organic EL device may be divided into blue, green, and red light-emitting materials according to the light-emitting color. In addition, yellow and orange light-emitting materials are also used as a light-emitting material for implementing a much better natural color. Further, a host/dopant system may be used as a light-emitting material in order to enhance color purity and light-emitting efficiency through an energy transfer. Dopant materials may be divided into a fluorescent dopant using an organic material and a phosphorescent dopant in which a metal complex compound including heavy atoms such as Ir and Pt is used. Since the development of the phosphorescent material may theoretically enhance light-emitting efficiency by up to 4 times compared to the development of the fluorescent material, interests in not only phosphorescent dopant, but also phosphorescent host materials have come into focus.
As the hole transporting layer, the hole blocking layer and the electron transporting layer, NPB, BCP, Alq3 and the like represented by the following Formulae have been widely known until now, and for the light-emitting material, anthracene derivatives have been reported as a fluorescent dopant/host material. In particular, for the phosphorescent material having a great advantage in terms of enhancing the efficiency, metal complex compounds including Ir, such as Firpic, Ir(ppy)3 and (acac)Ir(btp)2, have been used as blue, green and red dopant materials. Until now, CBP have exhibited excellent characteristics as a phosphorescent host material.

However, the existing materials are advantageous in terms of light-emitting characteristics, but have a low glass transition temperature and very poor thermal stability, and thus fall short of a level that sufficiently satisfies the lifespan in the organic EL device.